DNSResolverTask.java
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00001 // Licensed under Apache License version 2.0
00002 package javax.jmdns.impl.tasks.resolver;
00003 
00004 import java.io.IOException;
00005 import java.util.Timer;
00006 import java.util.logging.Level;
00007 import java.util.logging.Logger;
00008 
00009 import javax.jmdns.impl.DNSOutgoing;
00010 import javax.jmdns.impl.JmDNSImpl;
00011 import javax.jmdns.impl.constants.DNSConstants;
00012 import javax.jmdns.impl.tasks.DNSTask;
00013 
00019 public abstract class DNSResolverTask extends DNSTask {
00020     private static Logger logger = Logger.getLogger(DNSResolverTask.class.getName());
00021 
00025     protected int         _count = 0;
00026 
00030     public DNSResolverTask(JmDNSImpl jmDNSImpl) {
00031         super(jmDNSImpl);
00032     }
00033 
00034     /*
00035      * (non-Javadoc)
00036      * @see java.lang.Object#toString()
00037      */
00038     @Override
00039     public String toString() {
00040         return super.toString() + " count: " + _count;
00041     }
00042 
00043     /*
00044      * (non-Javadoc)
00045      * @see javax.jmdns.impl.tasks.DNSTask#start(java.util.Timer)
00046      */
00047     @Override
00048     public void start(Timer timer) {
00049         if (!this.getDns().isCanceling() && !this.getDns().isCanceled()) {
00050             timer.schedule(this, DNSConstants.QUERY_WAIT_INTERVAL, DNSConstants.QUERY_WAIT_INTERVAL);
00051         }
00052     }
00053 
00054     /*
00055      * (non-Javadoc)
00056      * @see java.util.TimerTask#run()
00057      */
00058     @Override
00059     public void run() {
00060         try {
00061             if (this.getDns().isCanceling() || this.getDns().isCanceled()) {
00062                 this.cancel();
00063             } else {
00064                 if (_count++ < 3) {
00065                     if (logger.isLoggable(Level.FINER)) {
00066                         logger.finer(this.getName() + ".run() JmDNS " + this.description());
00067                     }
00068                     DNSOutgoing out = new DNSOutgoing(DNSConstants.FLAGS_QR_QUERY);
00069                     out = this.addQuestions(out);
00070                     if (this.getDns().isAnnounced()) {
00071                         out = this.addAnswers(out);
00072                     }
00073                     if (!out.isEmpty()) {
00074                         this.getDns().send(out);
00075                     }
00076                 } else {
00077                     // After three queries, we can quit.
00078                     this.cancel();
00079                 }
00080             }
00081         } catch (Throwable e) {
00082             logger.log(Level.WARNING, this.getName() + ".run() exception ", e);
00083             this.getDns().recover();
00084         }
00085     }
00086 
00096     protected abstract DNSOutgoing addQuestions(DNSOutgoing out) throws IOException;
00097 
00107     protected abstract DNSOutgoing addAnswers(DNSOutgoing out) throws IOException;
00108 
00114     protected abstract String description();
00115 
00116 }
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zeroconf_jmdns
Author(s): Daniel Stonier
autogenerated on Tue Nov 6 2012 14:18:57